Avalanche Forecast

Moderate - Uncertainty is due to how quickly the snowpack will recover and gain strength.

A weak ridge of high pressure will strengthen over the Interior and generate strong outflow winds along with residual flurries for the weekend. A warm front is expected to invade the region Monday night, with widespread snow and significantly warmer temperatures. 

SATURDAY NIGHT: Overcast. 6-8 cm of snow expected. Light southwest winds trending to strong at higher elevations. Treeline high around -10 C. 

SUNDAY: Overcast. Possible trace of snow expected. Light southwest wind trending to strong at higher elevations. Treeline high around -7 C. Possible temperature inversion setting up.

MONDAY: Mostly clear, with increasing cloud through the day. Possible trace of snow expected. Moderate south winds trending to strong southwest at higher elevations. Freezing level rising to around 500 m. A temperature inversion could mean that the temperature above 2000 m will be above -5 C.

TUESDAY: Mostly cloudy. 5-15 cm of snow expected. Moderate to strong southwest wind trending to extreme at higher elevations. Possibly above 100 km/h. Freezing level rising to around 800 m.

On Friday, several natural and rider triggered storm slab avalanches up to size 2 were reported by professional operations in the region. Avalanche control with explosives produced size 2.5 to 3.5 avalanches, mostly in the storm snow.

Thursday, riders released multiple small storm slab avalanches on small terrain features as the storm snow accumulated. Few natural loose dry avalanches were also observed on steep terrain features at treeline and below treeline. 

Although the persistent Dec crust/facets layer has recently been more active south and east of this region (details and photos here) it remains a concern in the Columbias as well. A very large storm slab avalanche (size 3) ran naturally in Mount Revelstoke National Park on Friday afternoon. Up to 3 m of snow buried the highway. This avalanche path rarely affects the road (only once every 5 or 10 years). The avalanche appears to have started as a storm slab, and stepped down to a deeper, persistent layer.

The region received 40 to 50 cm low-density snow and consistent 50 km/h southerly wind since the start of the storm Thursday. This snow few on a variety of surfaces, thin sun crust on solar aspects, isolated surface hoar at treeline on sheltered slopes, fresh wind slabs in lee alpine features at treeline and above or even previous storm snow (20-60 cm) from the last weekend's storm.

We're actively monitoring the early December crust. In some places, it's scoured and on the surface, while in wind-loaded terrain features it can be found as deep as 150 cm below the surface. It consists of faceted grains above a bulletproof crust formed by the Atmospheric Rivers of early December. There has been isolated avalanche activity on this crust in the last week that seems to be confined to complex alpine terrain. 

• Don't be too cavalier with decision making, storm slabs may remain sensitive to human triggering.
• Keep in mind that human triggering potential persists as natural avalanching tapers off.
• Be aware of the potential for loose avalanches in steep terrain where snow hasn't formed a slab.
• Be carefull with sluffing in steep terrain, especially above cliffs and terrain traps.
• Storm slabs in motion may step down to deeper layers resulting in large avalanches.